Malignant B cells from the majority of childhood acute lymphoblastic leukaemia (ALL) cases are characterised by the surface expression of CD10, previously known as common acute lymphoblastic leukaemia antigen or CALLA (as reviewed in LeBien and McCormack, 1989; Shipp and Look, 1993; Weir and Borowitz, 2001). This evidence concerns the gene MME and acute lymphoblastic leukemia.